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CVE-2026-53728— Medplum - Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage

Quick assessment

Affected
medplum medplum
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Medplum 是一个用于开发医疗健康类应用程序的开发者平台。在 5.1.6 版本之前，位于 的外部身份提供者（IdP）回调接口存在漏洞：它接受的攻击者可控制的跳转 URI（redirect URI）只需以已注册的客户端跳转 URI 为前缀即可，而不要求精确匹配。在成功完成外部 IdP 登录之后，服务器会将 Medplum 的登录信息（login）和授权码（code）拼接到该攻击者提供的 URL 后，并发起跳转。由于外部登录请求中的 state（状态参数）是以原始 JSON 形式序列化、并在后续回调中被直接信任的，

CVSS 7.1 · High

Affected Version Matrix 1

VendorProduct Version RangeStatus
medplum medplum < 5.1.6 affected
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I. Basic Information for CVE-2026-53728

Vulnerability Information
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Vulnerability Title
Medplum - Improper Validation of Redirect URI in External Auth Callback allows Authorization Code Leakage
Source: CVE Program / CVE List V5
Vulnerability Description
Medplum is a developer platform that enables development of healthcare apps. Prior to version 5.1.6, the external identity provider callback at GET /auth/external accepts attacker-controlled redirect URIs that only need to start with a registered client redirect URI, rather than matching exactly. After a successful external IdP login, the server appends Medplum login and code values to that attacker-supplied URL and issues a redirect. Because the external login request state is serialized as raw JSON and later trusted by the callback, an attacker who can tamper with state.redirectUri can cause Medplum to redirect authorization artifacts to an attacker-controlled endpoint. When the registered redirect URI is a bare origin or another prefix that can be extended into a different hostname, this becomes a cross-origin authorization code leak. This issue has been patched in version 5.1.6.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
指向未可信站点的URL重定向(开放重定向)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
medplum medplum < 5.1.6 -

II. Public POCs for CVE-2026-53728

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III. Intelligence Information for CVE-2026-53728

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Patches & Fixes for CVE-2026-53728 (2)

Vendor Advisories for CVE-2026-53728 (1)

Vendor Pages for CVE-2026-53728 (1)

IV. Related Vulnerabilities

Same product: medplum
Same vendor: medplum
Same weakness: CWE-601

V. Comments for CVE-2026-53728

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